• Title, Summary, Keyword: Wear Mechanism

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Wear Characteristics of the Extruded Bars of Hypereutectic Al-Si Alloy Powders produced by Rapid Solidification Process (급속응고법으로 제조한 과공정 Al-Si합금분말 압출재의 마멸특성)

  • Ahn, Young-Nam;Cho, Gue-Serb;Ra, Hyung-Yong
    • Journal of Korea Foundry Society
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    • v.14 no.5
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    • pp.447-454
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    • 1994
  • Wear resistance and wear mechanism of hypereutectic Al-($15{\sim}40$)wt%Si alloys were investigated. Primary Si particles under $20{\mu}m$ size were formed in hypereutectic Al-Si alloy powders due to rapid solidification. But the Si particles of extruded bars were finely distributed in smaller size than that of atomized powders. The wear mechanism of hypereutectic Al-Si alloys was divided into three types of wear phenomena, which were abrasive wear, delamination wear and severe adhesive wear according to sliding speed and load. At low sliding speed and load, wear mechanism was abrasive wear, so Al-15wt%Si alloy showed the best wear resistance. At high sliding speed and load, wear mechanism was adhesive wear, and Al-40wt%Si alloy showed the best wear resistance.

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Wear Mechanism of Tube Fretting Affected by Support Shapes

  • Kim, Hyung-Kyu;Lee, Young-Ho;Yoon, Kyung-Ho;Kang, Heung-Seok;Song, Kee-Nam;Ha, Jae-Wook
    • KSTLE International Journal
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    • v.3 no.1
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    • pp.68-73
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    • 2002
  • A fretting wear experiment in roam temperature air was performed to evaluate the wear mechanism of fuel rod using a fretting wear tester, which has been developed for experimental study, The main focus was to compare the wear behaviors of fuel rod against support springs with different contact contours (i.e. concave and convex). Wear volume, degree or surface hardening and adhesion tendency of wear particle were examined by the surface roughness tester. The result indicated that with a change of contact condition from contact force of 5 N to 0.1 mm gap, the wear volume of tube increased in the condition of concave spring, but slowly decreased in convex spring. From the results of SEM observation, wear mechanism of each test condition was also dependent on the spring shapes. The wear mechanism of each test condition in room temperature air is discussed.

Fracture Mechanics Study on Wear Mechanism of Ceramics -Discussions on Experimental Results of Wear Test- (세라믹의 마멸기구에 관한 파괴역학적 연구 -마멸실험 결과의 고찰-)

  • 김석삼;김재호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.3
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    • pp.636-645
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    • 1990
  • Analytically induced wear mechanism of elastic body under Hertzian contact is applied in acutual wear test of ceramics. There are two types of wear in ceramics, a large scale wear and a small scale wear. The large scale wear is commensurable with Hertzian contact area and the small scale wear with real contact area. Nondimensional parameter, S$_{c}$, is introduced and fully examined to estimate or predict wear rate of ceramics. Ceramic wear for S$_{c}$.leq.0.8 is in small scale wear and for S$_{c}$;geq.1.6 in large scale wear. wear.

A Study on the Corrosive Wear Mechanism on Atmospherical Temperature of STS 304 Steel (STS 304강의 분위기온도에 따른 부식마멸기구에 관한 연구)

  • 전태옥;박흥식;주창식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.2
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    • pp.399-406
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    • 1990
  • This paper is studied to know corrosive wear mechanism of STS304 steel on atmospherical temperature against mating material as the same. The corrosive test was carried out by rubbing the annular surface of two test pieces in distilled water and NaCl aqueous solution. The corrosive wear mechanism was investigated by S.E.M. The experimental results show that there is one Lcr transferring from severe wear to mild wear on change of NaCl concentration and atmospherical temperature, and which is the other still remaining in server wear state. It was found that the critical sliding distance Lcr shorten with increasing NaCl concentration but it is longer with ascending atmospherical temperature and the mild wear state still continues under the condition of high generation rate and elimination rate of the corrosive product. Considering upon the result, the model of corrosive wear mechanism is proposed.

A Study on The Wear Process and Wear Mechanism of the Alumina Ceramics with Different Alumina Purity (순도를 달리한 알루미나 세라믹스의 마멸과정 및 이의 기구에 관한 연구)

  • 전태옥;진동규
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3404-3412
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    • 1994
  • The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.

Lubricating Mechanism Analyzed from Wear Characteristics of Polyolester Base Oils Haying different Branch Shapes(II) (서로 다른 모양의 가지사슬을 갖는 폴리올에스터 오일의 마모특성으로부터 해석된 윤활작용 메커니즘(II))

  • 한두희;마사부미마스꼬
    • Tribology and Lubricants
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    • v.17 no.3
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    • pp.171-178
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    • 2001
  • In order to elucidate the lubricating mechanism of polyolester base oils [POEs], the wear characteristics of 27 kinds of polyolester base oils including mixed POEs were investigated. Their wear results were discussed in terms of the effect of molecular structure on wear performance and compared with those of mineral oil. In addition, the adsorption ability of POEs to reduced iron and their hydrolysis rates were measured and the effect of their molecular structures on the adsorptivity and hydrolysis rate of POEs was discussed, respectively. Finally, the lubricating mechanism anlyzed from these results of wear characteristics, adsorptivity and hydrolysis rate was proposed. That is to say, POEs are firstly adsorbed to friction surface and decomposed by hydrolysis or thermal degradation. Fatty acids obtained by degradation of POEs form adsorption film on friction surface. The larger become cohesive ability among fatty acid molecules in the adsorption film, the better gets the wear performance of POEs.

A Study on the Wear Characteristics and the Mechanism of KP-4M Steel for Plastic Molding (플라스틱성형용 KP-4M강의 마멸특성 및 이의 기구에 관한 연구)

  • 박흥식;전태옥;김동호
    • Tribology and Lubricants
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    • v.12 no.1
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    • pp.22-28
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    • 1996
  • This study was undertaken to investigate the dry wear characteristics and mechanism of KP-4M steel for plastic molding against SKD 61 hardened by heat treatment. The wear test was carried out under different conditions such as sliding speed, contact pressure, sliding distance, with frictional tester of pin on disc type. The wear loss on variation of sliding speed was little in lower speed range below 0.5 m/sec and in higher speed range above 1.5 m/sec,'but wear loss was high in intermediate speed range. The critical sliding speed, which showed the maximum value of specific wear rate, became lower with increased contact pressure. Increasing the contact pressure, the critical sliding distance Lcr which the wear mechanism changes from severe wear to mild wear was increased due to the decrease of oxidation reaction velocity. Through this study we suggested a model of generation and elimination process of wear debris of KP-4M steel for plastic molding.

Comparison of Wear Property Between Metal and Polymer Matrix Composites (금속복합재료와 고분자복합재료의 마모 특성 비교)

  • KIM, Jae-Dong
    • Journal of Fisheries and Marine Sciences Education
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    • v.28 no.6
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    • pp.1875-1881
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    • 2016
  • The wear behavior for the two types of composites, those are epoxy matrix composites filled with silica particles and aluminium matrix composites filled with SiC particles, were compared to investigate the wear mechanism for these composites. Especially, the effect of the volume fraction for the epoxy matrix composites and the particle size for the aluminium matrix composites according to the apply load and sliding velocity were investigated. Wear tests of the pin-on-disc mode were carried out and followed by scanning electron microscope observations for the worn surface. The addition of the fillers in the composites were improved the wear resistance significantly and changed the wear mechanism for the both composites. These results were identified by the observation of the worn surface after testing.

A study on wear mechanism of tube fretting affected by support shapes (지지부 형상에 따른 튜브 프레팅 마멸기구의 연구)

  • Lee, Yeong-Ho;Kim, Hyeong-Gyu;Ha, Jae-Uk
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.73-79
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    • 2002
  • Fretting wear test in room temperature air was performed to evaluate the wear mechanism of fuel rod using a fretting wear tester, which has been developed for experimental study. The main focus was to compare the wear behaviors of fuel rod against support springs at different contact geometries (i.e. concave and convex) and slip directions (axial and transverse). The wear on the tube was examined by the surface roughness tester, which measures the volume. The result indicated that with change of contact geometry from 5N of normal load to 0.1mm gap, wear volume of tube Increased in the condition of concave spring, but slowly decreased in convex spring. From the results of SEM observation, wear mechanism of each test condition was also depend on the above contact parameters. The wear mechanism of each test condition in room temperature air is discussed.

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Wear Characterization of $Al/Al_2O_3$ Composites Reinforced with Hybrid of Carbon Fibers and SiC Whiskers (탄소섬유와 SiC 휘스커를 혼합한 $Al/Al_2O_3$ 복합재료의 마멸특성)

  • 봉하동;송정일;한경섭
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.7
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    • pp.1619-1629
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    • 1995
  • The Al/Al$_{2}$O$_{3}$ SiC and Al/Al$_{2}$O$_{3}$/C hybrid metal matrix composites (MMCs) were fabricated by squeeze infiltration method. Uniform distribution of reinforcements were found in the microstructure of metal matrix composites. Mechanical tests were carried out under various test conditions to clearly identify mechanical behavior of MMCs, and the wear mechanism of Al/Al$_{2}$O$_{3}$/(SiC or C) hybrid metal matrix composites were investigated. The tensile strength and hardness of hybrid composites was resulted in increasing compared with those of the unreinforced matrix alloy. Wear resistance was strongly dependent upon kinds of fiber, volume fraction and sliding speed. The wear resistance of metal matrix composites was remarkably improved by the addition of reinforcements. Especially, the wear resistance of the hybrid composites of carbon fibers was more effective than in the composites reinforced with alumina and SiC whiskers of reinforcements. This was due to the effect of carbon fiber on the solid lubrication. Wear mechanisms of hybrid composites were suggested from wear surface analyses. The major wear mechanism of hybrid composites was the abrasive wear at low to intermediate sliding speed, and the melting wear at intermediate to high sliding speed.